Gerotor pump

ABSTRACT

Provided is a gerotor pump including an inner rotor connected to a driving axis of a motor to transfer rotation force, an outer rotor formed at an outer side of the inner rotor, and a casing receiving the inner and outer rotors therein and provided with an inlet and an outlet, the inner and outer rotors forming several closed chambers while eccentrically rotating, having a predetermined clearance therebetween, to transfer a fluid, wherein a pressure chamber is formed in the casing in a direction in which force acts on the outer rotor by pressure of the fluid to offset the force, such that frictional force between the outer rotor and the casing decreases, thereby making it possible to improve performance and efficiency of the pump.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2011-0102699, filed on Oct. 7, 2011, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The following disclosure relates to a gerotor pump, and more particularly, to a gerotor pump including an inner rotor connected to a driving axis of a motor to transfer rotation force, an outer rotor formed at an outer side of the inner rotor, and a casing receiving the inner and outer rotors therein and provided with an inlet and an outlet, the inner and outer rotors forming several closed chambers while eccentrically rotating, having a predetermined clearance therebetween, to transfer a fluid, wherein a pressure chamber is formed in the casing in a direction in which force acts on the outer rotor by pressure of the fluid to offset the force, such that frictional force between the outer rotor and the casing decreases, thereby making it possible to improve performance and efficiency of the pump.

BACKGROUND

A gerotor pump, which is a typical positive displacement pump having a flow amount changed in proportion to a rotation speed of a motor, is configured to include an inner rotor connected to a driving axis of the motor to transfer rotation force and an outer rotor, wherein the inner and outer rotors form several closed pumping chambers while eccentrically rotating, having a predetermined clearance therebetween, to transfer a fluid.

That is, the rotors rotate around their central axes, and a pumping chamber becomes large at an inhalation side and becomes small at a discharge side in a rotation direction to transmit the fluid in a uniform fluid amount.

More specifically, as shown in FIG. 1, an outer side of an inner rotor 10 of a general gerotor pump is provided with N lobes and an inner side of an outer rotor 20 thereof is provided with N+1 lobes 21, and the lobes 11 and 21 are engaged with each other, such that the inner and outer rotors 10 and 20 rotate in a rotation ratio of (N+1)/N (See Korean Patent No. 10-0695934).

In addition, the inner and outer rotors 10 and 20 rotate while having a predetermined eccentricity. Due to this eccentricity, a pumping chamber A capable of transferring fluid fuel is formed between the inner and outer rotors 10 and 20.

Here, as shown in FIG. 2, the inner rotor 10 and the outer rotor 20 are seated in a casing 30, an inhalation channel 31 and a discharge channel 32 are formed in the casing 30 so as to be symmetrical to each other, and a sealing plate 40 is closely adhered to the inner and outer rotors 10 and 20.

Therefore, a volume of the pumping chamber A repeatedly increases and decreases during rotation of the inner and outer rotors 10 and 20. Here, a portion at which the volume of the pumping chamber increases becomes a vacuum state, such that a fluid is inhaled through the inhalation channel 31, and a portion at which the volume of the pumping chamber decreases has increased pressure, such that the fluid is discharged through the discharge channel 32.

However, force pulling the outer rotor 20 acts at a portion at which the pressure of the pumping chamber A decreases while the volume thereof increases, and force pushing the outer rotor 20 outwardly acts at a portion at which the pressure of the pumping chamber A increases while the volume thereof decreases.

Therefore, fractional force increases on a contact surface between the outer rotor 20 and the casing 30, such that performance of the pump is deteriorated, and abrasion on the contact surface occurs, such that a lifespan of the pump decreases.

RELATED ART DOCUMENT Patent Document

-   KR 10-0695934 B1 (Mar. 9, 2007)

SUMMARY

An embodiment of the present invention is directed to providing a gerotor pump including an inner rotor connected to a driving axis of a motor to transfer rotation force, an outer rotor formed at an outer side of the inner rotor, and a casing receiving the inner and outer rotors therein and provided with an inlet and an outlet, the inner and outer rotors forming several closed chambers while eccentrically rotating, having a predetermined clearance therebetween, to transfer a fluid, wherein a pressure chamber is formed in the casing in a direction in which force acts on the outer rotor by pressure of the fluid to offset the force, such that frictional force between the outer rotor and the casing may decrease.

In one general aspect, a gerotor pump includes: a lower casing 100 having an inhalation channel 120 formed in an upper surface thereof so as to be in communication with an inlet 110 formed at one side thereof; an upper casing 200 coupled to an upper side of the lower casing 100 and having a discharge channel 220 formed in a lower surface thereof so as to be in communication with an outlet 210 formed at one side thereof; and a gerotor 300 received between the upper and lower casings 100 and 200 and having inner and outer rotors 310 and 320 engaged with each other so as to eccentrically rotate, wherein the upper casing 200 includes a pressure chamber P formed at a discharge chamber D side of an inner peripheral surface thereof contacting the outer rotor 320, the pressure chamber P being in communication with the outlet 210 of the upper casing 200.

In another general aspect, a gerotor pump includes: a lower casing 100 having an upper portion formed to be opened and having an inhalation channel 120 formed in an upper surface thereof so as to be in communication with an inlet 110 formed at one side thereof; a gerotor 300 received in the lower casing 100 and having inner and outer rotors 310 and 320 engaged with each other so as to eccentrically rotate; and a flexible plate 400 coupled to an upper surface of the gerotor 300 and made of a flexible material so as to selectively form a discharge channel 410 by internal pressure of the gerotor 300, wherein the lower casing 100 includes a pressure chamber P formed at a discharge chamber D side of an inner peripheral surface thereof contacting the outer rotor 320, the pressure chamber P being in communication with the discharge channel 410.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an inner rotor and an outer rotor of a gerotor pump according to the related art.

FIG. 2 is a cross-sectional view showing the gerotor pump according to the related art.

FIG. 3 is a cross-sectional view showing a gerotor pump according to an exemplary embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a pressure chamber formed in a case according to the exemplary embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a gerotor pump according to another exemplary embodiment of the present invention.

[Detailed Description of Main Elements] 100: lower casing 110: inlet 120: inhalation channel 130: pressure channel 200: upper casing 210: outlet 220: discharge channel 230: pressure channel 300: gerotor 310: inner rotor 311: lobe 320: outer rotor 321: lobe 400: flexible plate 410: discharge channel 500: armature 510: shaft 600: pump housing I: inhalation chamber D: discharge chamber P: pressure chamber S: stop portion

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, a gerotor pump according to an exemplary embodiment of the present invention as described above will be described in detail with reference to the accompanying drawings.

FIG. 3 is a cross-sectional view showing a gerotor pump according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the gerotor pump according to the exemplary embodiment of the present invention is configured to include a lower casing 100 having an inhalation channel 120 formed in an upper surface thereof so as to be in communication with an inlet 110 formed at one side thereof; an upper casing 200 coupled to an upper side of the lower casing 100 and having a discharge channel 220 formed in a lower surface thereof so as to be in communication with an outlet 210 formed at one side thereof; and a gerotor 300 received between the upper and lower casings 100 and 200 and having inner and outer rotors 310 and 320 engaged with each other so as to eccentrically rotate.

Here, the upper casing 200 includes a pressure chamber P formed at a discharge chamber D side of an inner peripheral surface thereof contacting the outer rotor 320, wherein the pressure chamber P is formed to be in communication with the outlet 210 of the upper casing 200.

First, the lower casing 100 includes the inlet 110 formed at one side thereof so as to penetrate through upper and lower surfaces thereof and includes the inhalation channel 120 formed in a groove shape in the upper surface so as to be in communication with the inlet 110.

The upper casing 200 is coupled to be closely adhered to the upper surface of the lower casing 100 and is configured to have an internal space formed at a lower side thereof so that the gerotor 300 is received therein.

In addition, the upper casing 200 includes the outlet 210 formed at one side thereof so as to penetrate through upper and lower surfaces thereof and includes the discharge channel 220 formed in the lower surface thereof so as to be in communication with the outlet 210.

Here, the gerotor 300 is received and seated in the internal space of the upper casing 200, the lower and upper casings 100 and 200 are coupled to each other, and the gerotor 300 rotates between the upper and lower casings 100 and 200.

In addition, the lower and upper housings 100 and 200 are inserted into a pump housing 600 in a state in which they are coupled to each other, such that outer sides thereof are fixed.

In this case, the gerotor 300 is configured to include the inner and outer rotors 310 and 320, wherein the inner rotor 310 is disposed at an inner side of the outer rotor 320.

In addition, referring to FIG. 4, the inner and outer rotors 310 and 320 are engaged with each other so as to eccentrically rotate, and the inner rotor 310 rotates in a state in which the center thereof is fixed to a shaft 510 of an armature 500. As the inner rotor 310 rotates, the outer rotor 320 eccentrically rotates.

In addition, the numbers of lobes 311 and 321 of each of the inner and outer rotors 310 and 320 are different from each other. More specifically, the number of lobes 321 of the outer rotor 320 is more than the lobes 311 of the inner rotor 310 by one.

Therefore, a fluid is inhaled or discharged by a volume change of a space between the lobes 311 and 321 of the inner and outer rotors 310 and 320 that are engaged with each other and rotates.

In this case, a plurality of inhalation chambers I corresponding to portions inhaling the fluid while volumes thereof increases are formed, and a plurality of discharge chambers D corresponding to portions discharging the fluid while volumes thereof decreases are formed, between the lobes 311 and 321 of the inner and outer rotors 310 and 320, based on a portion at which teeth forms are completely coupled to each other.

In addition, a stop portion S of which a volume is not changed is formed at the center of the inhalation chambers I and the discharge chambers D along a circumferential direction of the gerotor 300.

That is, the volume change occurs between the lobes 311 and 321 at the time of rotation of the gerotor 300 due to a difference between the numbers of lobes 311 and 321 of the inner and outer rotors 310 and 320, thereby inhaling and discharging the fluid.

Here, the inhalation channel 120 formed in the lower casing 100 may be lengthily formed in a groove shape in the circumferential direction so as to be in communication with the inhalation chamber I, and the discharge channel 220 formed in the upper casing 200 may be lengthily formed in a groove shape in the circumferential direction so as to be in communication with the discharge chamber D.

Therefore, the fluid is introduced through the inlet 110 of the lower casing 100, is inhaled to the inhalation chamber I through the inhalation channel 120, and is compressed while the volume of the discharge chamber D decreases, such that it is discharged to the outlet 210 through the discharge channel 220 of the upper casing 200 and is transferred to an inner portion of the pump housing 600.

In this case, due to vacuum pressure generated while the volume of the inhalation chamber I increases and discharge pressure generated while the volume of the discharge chamber D, force acts on the inner and outer rotors 310 and 320 in a specific direction.

In addition, the inner and outer rotors 310 and 320 form the inhalation chambers I, the stop portion S, and the discharge chambers D while rotating in the upper casing 200. Since the inhalation chambers I, the stop portion S, and the discharge chambers D are repeatedly formed at a predetermined region, force always acts in the same direction.

That is, as shown in FIG. 4, the force acts on the inner rotor 310 in a direction toward the inhalation chamber I based on the center. To the contrary, the force acts on the outer rotor 320 in a direction toward the discharge chamber D based on the center.

Here, the inner rotor 310 is fixed in a radial direction by the shaft 510 of the armature 500, such that frictional force caused by force due to pressure of the fluid is small. However, the outer rotor 320 is fixed in the radial direction in a state in which it contacts the inner peripheral surface of the upper casing 200, such that frictional force caused by force due to pressure of the fluid is large due to a wide contact area.

Therefore, in order to decrease the frictional force, force at which the outer rotor 320 is pushed toward the inner peripheral surface of the upper casing 200 by the pressure of the fluid needs to decrease.

Here, the gerotor pump according to the exemplary embodiment of the present invention includes the pressure chamber P formed at the discharge chamber D side of the inner peripheral surface of the upper casing 200 contacting the outer rotor 320, wherein the pressure chamber P is formed to be in communication with the outlet 210 of the upper casing 200.

That is, a pressure channel 230 is formed at one side of the upper casing 200 and the pressure chamber P is formed to be in communication with the pressure channel 230, such that the fluid discharged through the outlet 210 is introduced into the pressure chamber P along the pressure channel 230.

Here, the fluid is introduced into the pressure chamber P along the pressure channel 230, such that the pressure chamber P is maintained in a state in which it is filled with the fluid, and pressure of the fluid filled in the pump housing 600 and pressure of the fluid filled in the pressure chamber P are maintained to be the same as each other.

Therefore, force acting on the outer rotor 320 by the pressure of the fluid in the discharge chamber D and force by the pressure of the fluid introduced into the pressure chamber P are offset to each other, such that the frictional force generated due to the contact between the outer peripheral surface of the outer rotor 320 and the inner peripheral surface of the upper casing 200 decreases.

As described above, in the gerotor pump according to the exemplary embodiment of the present invention, when the inner and outer rotors form the plurality of closed inhalation chambers and discharge chambers while eccentrically rotating, having a predetermined clearance therebetween, to transfer the fluid, the pressure chamber is formed in the upper casing in a direction in which the force acts on the outer rotor by the pressure of the fluid to offset the force, such that the frictional force between the outer rotor and the upper casing decreases, thereby making it possible to improve performance and efficiency of the pump.

Here, in order for the pressure chamber P to offset the force acting on the outer rotor 320 by the pressure of the fluid, an area and a position of the pressure chamber P formed to contact the outer rotor 320 need to be appropriately selected. It is preferable that the pressure chamber P is formed to be positioned at a central portion of a thickness of the outer rotor 320 and is formed to be symmetrical based on a central portion of the discharge chamber D in the circumferential direction, as shown.

In addition, a gerotor pump according to another exemplary embodiment of the present invention is configured to include a lower casing 100 having an upper portion formed to be opened and having an inhalation channel 120 formed in an upper surface thereof so as to be in communication with an inlet 110 formed at one side thereof; a gerotor 300 received in the lower casing 100 and having inner and outer rotors 310 and 320 engaged with each other so as to eccentrically rotate; and a flexible plate 400 coupled to an upper surface of the gerotor 300 and made of a flexible material so as to selectively form a discharge channel 410 by internal pressure of the gerotor 300, wherein the lower casing 100 includes a pressure chamber P formed at a discharge chamber D side of an inner peripheral surface thereof contacting the outer rotor 320, the pressure chamber P being formed to be in communication with the discharge channel 410.

The gerotor pump according to another exemplary embodiment of the present invention is similar to the gerotor pump according to the exemplary embodiment of the present invention described above except that the gerotor is received in the lower casing 100 and the flexible plate 400 made of the flexible material is disposed at an upper side of the gerotor 300, such that the flexible plate 400 is selectively opened at a portion at which the discharge chamber D is formed while rotating together with the gerotor 300 to discharge a fluid, as shown in FIG. 5.

Here, the flexible plate 400 is coupled to the upper surface of the gerotor 300 so as to be closely adhered thereto and is made of the flexible material. Therefore, when pressure in the discharge chamber D increases while a volume of the discharge chamber D decreases, a portion of the flexible plate 400 is opened upwardly, such that the fluid is discharged.

That is, the discharge channel 410 is not separately formed, but is an opened space of the flexible plate 400 opened upwardly by the pressure of the fluid in the discharge chamber D formed in the gerotor 300 and disposed at an upper side of the discharge chamber D.

Here, the pressure chamber P is formed in the lower casing 100, the flexible plate 400 is opened upwardly at the portion at which the discharge chamber D is formed, such that the discharge channel 410 is formed, and the discharged fluid is introduced into the pressure chamber P along the pressure channel 130 formed in the lower casing 100. Therefore, similar to the exemplary embodiment described above, force acting on the outer rotor 320 by the pressure in the discharge chamber D and force by the pressure in the pressure chamber P are offset to each other, thereby making it possible to decrease frictional force on a contact surface between the outer rotor 320 and the lower casing 100.

In the gerotor pump according to the exemplary embodiment of the present invention, when the inner and outer rotors form several closed pumping chambers while eccentrically rotating, having a predetermined clearance therebetween, to transfer the fluid, the pressure chamber is formed in the casing in a direction in which the force acts on the outer rotor by the pressure of the fluid to offset the force, such that the frictional force between the outer rotor and the casing decreases, thereby making it possible to improve performance and efficiency of the pump.

The present invention is not limited to the above-mentioned exemplary embodiments but may be variously applied, and may be variously modified by those skilled in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. 

What is claimed is:
 1. A gerotor pump comprising: a lower casing having an inhalation channel formed in an upper surface thereof so as to be in communication with an inlet formed at one side thereof; an upper casing coupled to an upper side of the lower casing and having a discharge channel formed in a lower surface thereof so as to be in communication with an outlet formed at one side thereof; and a gerotor received between the upper and lower casings and having inner and outer rotors engaged with each other so as to eccentrically rotate, wherein the upper casing includes a pressure chamber formed at a discharge chamber side of an inner peripheral surface thereof contacting the outer rotor, the pressure chamber being in communication with the outlet of the upper casing.
 2. A gerotor pump comprising: a lower casing having an upper portion formed to be opened and having an inhalation channel formed in an upper surface thereof so as to be in communication with an inlet formed at one side thereof; a gerotor received in the lower casing and having inner and outer rotors engaged with each other so as to eccentrically rotate; and a flexible plate coupled to an upper surface of the gerotor and made of a flexible material so as to selectively form a discharge channel by internal pressure of the gerotor, wherein the lower casing includes a pressure chamber formed at a discharge chamber side of an inner peripheral surface thereof contacting the outer rotor, the pressure chamber being in communication with the discharge channel. 